Small, manually operated or motorized winches have innumerable applications and are used for a variety of tasks, including raising and lowering flags on flagpoles. When used with a flagpole, the winches may be mounted to the outside of the pole or inside the hollow interior, as is the case with internal halyard flagpole designs. In spite of their increased expense, interior mounted winches are quite popular as they offer several advantages over exterior winches. The flush outer surface of a flagpole with an interior winch is both more aesthetically pleasing and safer than an exterior winch, as it eliminates the potential bump hazard caused by a hard, protruding object at torso level. An additional advantage comes from having both the winch and the cord enclosed within the flagpole and protected from the elements, which significantly extends the useful life of the winch system. And finally, it is easier to secure a flagpole with an internal winch from unauthorized tampering or vandalism as both the winch and the reachable section of the cord can be secured behind a locked door or access cover.
Internal winches are not without problems of their own, however. An access passage for installing and operating the winch must be drilled or machined into the side of the flagpole near its base, which may create regions with high stress concentration factors that significantly weaken the overall pole structure. And because entry to the apparatus is constrained by the size of the opening, some traditional winch designs, such as the common ratchet winch, are precluded from being installed inside the flagpole. Furthermore, maintenance and repair operations also become more difficult with the restricted access to the components of the winch located inside the flagpole.
The internal winch is also limited in capacity by the outer frame and support structure of the apparatus, otherwise known as the shield. As the volume between the cord spool and the shield is finite, both the amount of available cord and the useful height of the flagpole are limited. The shield also contributes to the common problem of clogging, which occurs when loops of the cord become bound inside the winch between the spool and the internal surface of the shield.
All these considerations must be taken into account in designing a flagpole winch that performs the basic functions of easily raising and lowering the flag, and then reliably locking the winch to secure the flag in its new position. It is important that the locking mechanism prevent the winch from unreeling despite severe weather conditions, such as stiff breezes and gusting winds that are capable of imparting instantaneous high loads on the brake or locking mechanism. It is an additional constraint that winch operations be inherently safe and easy to operate since flagpole duties are often given to the young or unskilled. And from an economic and manufacturing perspective, it would be more cost-effective to produce a family of internal flagpole winches of standardized sizes that could readily be adapted to fit into uncut stock flagpoles of different diameters using simple machining methods.
One of the more common internal winch designs used in flagpoles is today is the brake winch. A brake winch typically has a square cross-sectional frame surrounding a cylindrical spool, with provisions for a detachable winch handle on one end of the spool and a cast bronze internal brake at the other. The internal brake is modeled after the brake drum on an automobile, with the exception that the brake winch only releases when rotational pressure is exerted by the winch handle. Like the drum brake on an automobile, however, the brake winch is subject to frictional wear and requires periodic maintenance.
While its simple and straightforward operation is an advantage, the installation of the brake winch creates significant problems. First, the square cross-section of the winch requires that a square hole to be machined into the sidewall of the flagpole. Even with large-radius corners, a square hole in the sidewall of the pole creates stress concentration factors sufficient to decrease the overall strength of the pole and move the weakest point of the structure from the base of the pole up to the winch location. To compensate at least in part, a welded reinforcement is often added around the edges of the opening and a door is installed over the breach to stiffen the pole when the winch is not actively being turned. However, any additional welding on the pole requires heat treatment to temper the new weld material, which heat treatment must be completed prior to anodizing the flagpole. These additional installation steps require that the flagpole be cut and prepared to receive the brake winch while still in the factory, and that distributors stock their inventory with a wide variety of poles in different configurations in order to quickly respond to customer orders.
One current alternative to the brake winch that alleviates some of the installation difficulties is the “M” winch, which is a smaller, self-locking winch having a cylindrical configuration. The round cross-section of the “M” winch only calls for a circular opening to be cut into the sidewall of the flagpole. This eliminates the need for additional reinforcement or welding because a smooth, round hole does not result in stress concentration factors high enough to significantly weaken the flagpole, as long as the opening is not too large. Furthermore, a round opening can be easily cut into a blank pole with a common hole saw, which facilitates field installation. Thus the “M” winch resolves many of the installation problems associated with brake winches.
However, the “M” winch does have issues relating to its operation. The “M” winch design uses a spool having a spring-loaded end plate with a number of axially orientated pins that fit within a series of machined slots in the housing. When the pins are engaged within the slots, the spool is locked. The winch is turned by first pushing inward on the handle to release the spins from the slots, and then rotating the handle to turn the spool. Operation of the “M” winch is more complicated than with a brake winch, as the user must simultaneously apply both inward pressure and rotational force while turning the device. Releasing the inward-directed force allows the spring-loaded spool to re-engage with the stationary slots and lock in its new rotational position. It has been observed, however, that on occasions when the winch is heavily loaded the end plate pins may skip backwards over the slots after the operator releases the handle. And if the winch is allowed to gain sufficient rotational momentum, the spool may unreel completely.
Another disadvantage of the “M” winch is that its capacity is even smaller than that of the brake winch design, as all the cord must fit within the shield's cylindrical housing. And because of the tight space between the shield and the spool, the “M” winch is more susceptible to clogging.